The invention relates to a filter module for removing air-polluting materials from machine exhaust, comprising a filter housing with an intake opening and an outlet opening for channeling machine exhaust through, at least one mounting element for mounting the filter module on a machine, and a filter assembly, arranged in the filter housing and comprised of at least two filter groups, arranged in tandem in the direction of flow and comprised of rod-shaped filter elements with a filter medium, said elements being arranged parallel to one another at a constant center-to-center distance and with their longitudinal axis largely crosswise to the direction of flow, wherein the filter elements of two adjacent filter groups are parallel to one another, and are arranged offset in relation to one another, crosswise to their longitudinal axes and to the direction of flow.
From U.S. Pat. No. 6,726,749 B2, a filter device of this type designed for removing air-polluting materials from the exhaust air from machines, especially office machines, is known. This device has a plurality of filter sticks in a filter housing, which sticks are supplied with fluid from a fluid container, and a fastening device for mounting the filter housing on a machine, wherein the filter rods are positioned in the exhaust air flow. As can be seen in FIG. 7 of the US publication, in one embodiment the filter rods are arranged in rows, and the rows are offset in relation to one another. The air-polluting materials are adsorbed as they pass by the filter rods wetted with the fluid, and are thereby removed from the exhaust air flow.
The disadvantage of this system is that each of the filter rods is mounted separately in the filter housing, so that maintenance or replacement of the filter rods is correspondingly laborious and tedious. Also disadvantageous is that the fluid is consumed when the filter device is in use, and the fluid container must be regularly refilled to extend its useful period, to maintain the wetting of the filter rods. This filling process requires a great deal of caution or additional accessories to prevent contamination. Independent of the supply with fluid, if the filter rods are badly soiled following an extended period of use or due to severely polluted machine exhaust, a reconditioning cleaning or replacement of the filter rods or of the entire filter device may be necessary, which, because of the individually attached filter rods, entails high costs from increased handling expenses or a complete replacement.
The object of the invention consists in providing a filter device of the described type that is characterized by a more simplified application and entails only low costs in its production and use.
The object of the invention is attained with a filter module for removing air-polluting materials from machine exhaust, comprising at least two parallel filter groups, arranged in an offset from one another in the direction of flow of exhaust, wherein each filter group includes a plurality of spaced-apart rod-shaped filter elements, and wherein at least two or more spaced-apart rod-shaped filter elements of at least one filter group are connected as a filter insert detachably coupling to a filter housing.
One advantage of the filter module of the invention is the combination of the filter elements with at least one filter bracket to create at least one filter insert, which can be removed from the filter housing. This allows the filter insert to be handled separately from the filter housing, for example in order to more easily clean the filter elements or the filter medium, to replace individual filter elements, or to exchange the entire filter insert. The filter bracket can be a strip-type element, to which the individual filter elements are attached, preferably orthogonally, parallel to one another, and at a constant center-to-center distance; the bracket may also be frame-shaped, for example, fastening both ends of the individual filter elements. The filter medium can be situated both on the outer surface of the filter elements and on the interior of the filter elements if the filter medium is capable of coming into contact with the exhaust air through openings in the surface of the filter elements, for example if the filter element is cage-like in structure.
A further advantageous effect is achieved with a configuration involving multiple filter inserts, especially if multiple rows of filter elements, preferably the individual filter groups, each with its own filter bracket, are combined. This allows the individual filter rows or filter groups to be cleaned or replaced independently of one another, based upon the degree of soiling, thereby reducing the cost of exchanging the filter inserts, since filter inserts that are still usable can continue to be used.
According to another embodiment of the filter module of the invention, offsetting the filter elements of two filter groups, which are arranged in tandem in the direction of flow, by half the center-to-center distance causes maximum redirection of the exhaust air as it passes by the filter elements, thereby improving the removal rate of the filter module.
The formation of a slide-in opening for the filter inserts in the filter housing enables more direct and better access to the individual filter inserts than through the intake opening or the outlet opening, since these permit only sequential access to the individual filter inserts. However, the slide-in opening can also be formed by a series of openings, through which the individual filter elements project into the interior of the filter housing, while the filter bracket remains outside of the filter housing.
According to a further improvement, for a secure positioning of the filter inserts in the filter housing it is advantageous to provide guide elements for securing the assembled position. These can be provided in the form of a longitudinal guide, along which the filter inserts are inserted into the filter housing, or in the form of localized guide elements, which come into force shortly before the proper slide-in position is reached.
One advantageous option for situating a filter insert in the installed position consists, according to a further embodiment, in configuring the slide-in opening as a guide element, wherein said element accommodates the filter bracket with a low level of play, which causes the installed filter insert to be secured crosswise to the slide-in direction. It is also possible to provide a separate slide-in opening for each filter insert, or to position the filter inserts snugly against one another through one common slide-in opening.
According to a further embodiment, an additional guide element configuration can be formed by a recess or opening in the filter housing opposite the slide-in opening, into which one or more filter elements or a frame-type filter bracket extend. Said recess can be limited to the housing wall alone, or can also be formed by a sleeve-like seating element that projects into the interior of the filter housing and accommodates an end section of the filter elements or the filter insert.
To achieve the offset between the filter elements of filter rows arranged in tandem, it is advantageous to offset the guide elements for the individual filter inserts in relation to one another. In this manner, the redirection of the exhaust air flow necessary to produce the cleaning effect is ensured.
For reasons of economic efficiency and user-friendliness it also makes sense, according to a further dependent claim, to configure the filter inserts that form a filter assembly to be structurally uniform. This makes manufacturing more cost-effective due to the larger number of pieces, and makes storage more cost-effective, while reducing the possibility of confusion for the user.
A further increase in user-friendliness can be achieved, according to a further characterizing feature, through a symmetrical configuration of the filter inserts. The more planes of symmetry a filter insert has, the lower the risk of inserting these incorrectly into the filter housing, allowing filter replacement to be performed without difficulty even by technical laypeople. The offset between the individual filter inserts in the embodiments having two or three planes of symmetry is effected by offsetting the guide elements and/or the slide-in openings.
According to a further embodiment, configuring the filter elements to have a large effective cross-section (in other words within a filter group the area of the filter elements that is projected in a plane perpendicular to the direction of flow is larger than the free passage area between the filter elements, which is projected in a plane perpendicular to the direction of flow) causes a sharp redirection when combined with the offset between the filter rows arranged in tandem, and the air-polluting materials contained in the exhaust air are adsorbed at a high level of probability. A further increase in the removal rate can be achieved by arranging more than two filter inserts in tandem, or multiple filter modules in tandem, although this will also increase flow resistance, which is permissible to only a limited extent, in order to avoid any unacceptable interference with the removal of heat from the machine producing the exhaust.
One possibility for reducing the costs of the filter inserts, according to a further dependent claim, consists in detachably connecting the filter elements to the filter bracket, which allows individual filter elements to also be replaced. Especially if the individual filter elements are loaded at different levels with the air-polluting materials or dust particles due to flow conditions, a replacement of individual filter elements can be advantageous. The filter elements can also be removed separately, which with certain embodiments of the filter elements (for example those having a star-shaped cross-section) or filter inserts can facilitate cleaning.
According to a further embodiment, it is advantageous for the filter elements to be attached to the filter bracket by means of a press fit, so that no additional means of attachment are necessary.
According to a described embodiment of the filter module, selecting the material for the filter medium from the group comprised of porous material, fibrous mesh, pulp material or a plastic foam is beneficial for positively influencing the removal rate of the filter module. On one hand, the pores and fibrous components in these materials act as supplementary mechanical collection surfaces, while on the other hand these materials can also serve as a storage medium for a chemically and/or physically active fluid, which adsorbs or absorbs the air-polluting materials. The porous material can be formed, for example, from a ceramic or metallic foam, which have a high level of mechanical stability and therefore are not prone to damage during assembly or cleaning. The fibrous mesh made of inorganic or organic and natural fibers, such as cellulose, cellulose acetate, polyester, etc., is also characterized by a high filtering effect. Plastic foams or latex foam can also be used as the filter medium, especially open-celled materials like PU foam, which is widely used as a wet-filter medium. For certain purposes, several different filter media can also be used in a filter assembly, to combine their respective advantageous properties.
By forming the filter elements from the same material as the filter medium, the filter volume can be substantially increased, allowing the service life of the filter inserts to be extended or the storage volume for fluid to be increased. Furthermore, the reduction in the number of materials used can decrease the cost of manufacturing the filter elements.
It can also be of benefit with certain embodiments to configure the filter medium and the filter element as a single piece, especially if the filter medium is sufficiently strong to withstand without damage the forces that occur during assembly and handling of the filter inserts, for example if the filter medium is sufficiently compressed. With the proper material selection, this can also serve to reduce manufacturing costs.
In a further embodiment of the filter module, the filter medium is provided on only a partial section of each filter element. Thus it is possible, for example, to provide the filter medium in a material-saving fashion only on the side of the filter elements that receives the flow. The expansion of the filter medium can also be limited to a section inside the filter element. In particular, the ends of the filter elements can be structured without filter medium, in order to facilitate attachment on the filter bracket or in the filter housing via a socket connection.
According to a further embodiment, providing the filter medium on the surface of the filter elements opens up a wide range of design possibilities for the shape of the supporting filter elements, and offers good accessibility if the filter elements should require cleaning. With the mentioned filter media it is somewhat difficult to produce complicated cross-sectional shapes, which is why in these cases a subsequent application on the surface of the filter elements is easier to produce. The connection between the filter medium and the filter elements can be mechanical, for example a clamping or spanning of the filter medium, and may involve a separate layer of adhesive or application of the filter medium in an adhesive state, for example by foaming the filter elements with a material that in its hardened state will form the filter medium.
According to a further embodiment, an improvement in the filtering effect of the filter module can be achieved by wetting the filter medium with a fluid selected from the group of fluids glycerin, silicone oil, essential oil, paraffin oil, and/or latex emulsion. The air-polluting materials in the machine exhaust, such as dust, fine dust, ultrafine particles, pollen, spores, bacteria, other aerosols with solid or liquid particles, and in the case of an office machine especially toner dust and/or paper wear debris, can be effectively bonded mechanically when they come in contact with the wetted filter medium, and gaseous pollutants, such as ozone, benzole, phenol, carbon dioxide, formaldehyde or unpleasant odors can also be chemically absorbed and/or neutralized by coming into contact with the fluid. One advantageous effect of these components consists in their low vapor pressure and correspondingly low evaporation rate, which produces a long service life. The viscosity of these fluids is further favorable to an even distribution in the filter medium via the capillary effect that occurs with the wetting of the filter medium. With a correspondingly adjusted high level of viscosity and surface tension, a direct wetting of the filter element is also possible, whereby the filter medium is formed by the fluid.
A further possible embodiment of the filter module consists in adding an olfactory substance to the fluid, allowing the air flowing out of the filter module to release a pleasant scent. By properly adjusting the concentration and the evaporation rate of the olfactory substance, the duration of scent release can be adjusted to the service life of the fluid, with the fading of the scent over time serving as an indicator of the need to change the filter elements or replace the fluid.
According to a further embodiment, it is also advantageous to add an antibacterial, antiviral, antimycotic or fungicidal substance to the fluid, whereby, on one hand, bacteria or mold spores emitted by the machine are rendered harmless when they come into contact with the fluid, and on the other hand the concentration or colonization of the filter elements with bacteria, viruses or fungi is prevented.
To prevent harm to the environment in the cleaning or disposal of the filter medium and/or filter elements that are wetted with the fluid, it is possible, according to one dependent claim, to use a wetting fluid that is readily biodegradable. The biochemical acid requirement for biological degradation in waste water (e.g. BSB5 value) and the Water Hazard Classification should be as low as possible.
Further, according to another embodiment of the filter module it is advantageous to equip the filter medium with an antibacterial surface. This can be accomplished, for example, with a coating or impregnation with silver, especially nanoscale silver, or a silver compound.
According to a further embodiment, it is advantageous to store the fluid within hollow spaces inside the filter elements, and to deliver it slowly to the filter medium via openings, such as small bore holes or slits. In this manner, fluid losses in the filter medium from evaporation can be continuously compensated for, and the service life of the filter elements can be extended.
A possible further improvement consists in forming at least a part of the filter medium from activated carbon, which is characterized by a high capacity for adsorbing polluting gases and odors. When combined with scent-releasing filter elements, the filter elements with activated carbon components in the filter medium should therefore be arranged in front of the scent-releasing filter elements, viewed in the direction of flow.
To remove ferromagnetic particles, such as iron wear debris, from the machine, one embodiment provides that one or more filter elements be equipped with a magnetic element or a magnetic component. This can be a permanent magnet or an electromagnet.
A further embodiment of the filter module is characterized by the fact that the rod-shaped filter elements have an elongate cross-section, in other words a cross-section with a prominent longitudinal axis. This increases the ratio of surface to volume of the filter elements, allowing a large filter surface to be accommodated in a relatively small amount of space.
According to a further embodiment, it is also advantageous to orient the longitudinal axes of the cross-sections crosswise to the direction of flow, in order to create large active surfaces and a sharp redirection of the exhaust air. With this arrangement of the filter elements, the filter module can be configured to be short, viewed in the direction of flow, with multiple filter inserts in tandem.
According to a further embodiment of the filter module, the cross-section of the filter elements can be rectangular, triangular, star-shaped or round in configuration. The rectangular, triangular or round, especially circular, embodiment of the filter elements is easy to produce in terms of manufacturing technology; the rectangular and circular cylindrical forms also favor a symmetrical configuration of the filter inserts. The star-shaped cross-section, in contrast, offers a high value in the ratio of surface to volume of the filter element, allowing a large filter surface to be accommodated in a relatively small space. The cross-sectional shape can also be used to influence the flow of exhaust air through the filter assembly, for example to eddy the flow through cross-sections that are unfavorable to flow, such as rectangular cross-sections, and to intensify contact of the exhaust air with the filter medium, or to calm the flow through cross-sections that are favorable to flow, such as triangular cross-sections, if the exhaust air flow from the machine is strong and turbulent and therefore potentially disruptive.
The mounting element for attaching the filter module to the machine emitting exhaust air can be advantageously comprised of a layer of adhesive, an adhesive strip, a Velcro strip, a screw, a locking pin, or a snap connector, wherein these fastening options are listed only as examples, and other fastening means can also be used. A Velcro connection between the filter housing and the machine especially provides easy assembly and handling by the user. The internal connection between the hook tape and the loop tape of the Velcro strip also acts as a seal between the machine and the filter housing, so that the exhaust air flow is guided largely through the filter module. However, a separate sealing element, such as a self-adhering sponge rubber strip, can also be used as a seal.
It is advantageous to position the mounting element in the area of the intake opening to the filter housing, in order to achieve small and cost-effective mounting components, and to make the attachment visually inconspicuous.
A further advantageous option for mounting the filter module is achieved by forming a groove on the rear side of the filter housing that faces the machine, into which an interconnecting element having an angular profile is inserted, and in that the interconnecting element is attached to the machine by means of the mounting element, preferably a Velcro strip.
According to a further, it is also advantageous to equip the filter housing with one or more connecting elements for connecting it to additional filter modules. Although it is naturally possible to adjust the size of a filter module to the exhaust air opening of the machine, in general it is more cost-effective to produce the filter modules in a uniform size and then assemble a filter device of the proper size by connecting multiple filter modules. Due to the many different types and sizes of machines in which the filter modules can be used, individual assembly from a standard size is more practical than a multitude of special production runs.
According to a further embodiment, the connection between two filter modules can be formed by a locking pin, a mounting rail or mounting groove, a dovetail connection, or a Velcro strip. However, any other types of connections, such as adhesives, screws, clamps, snap connections, etc., may also be used.
According to a further embodiment, in which the edges of two boundary walls of two filter housings are encompassed by a clamp element, can advantageously be implemented on the front side and/or the rear side of the filter housing. The clamp element is configured, for example, as a U-profile, which, when applied, achieves the clamping effect via a press fit.
For easier handling of the filter inserts it is further advantageous for the filter insert to have a handle element on the filter bracket, with which a user can grasp the filter insert when it is installed.
According to a further embodiment, producing the components of a filter module, especially of the filter housing, the filter bracket and/or the filter element, using a plastic injection molding process is economical especially when large piece numbers are required, and achieves consistently high workpiece precision levels and quality. In selecting the plastic to be used, the temperature of the exhaust air must be taken into account, so that during use, no impermissible shape changes in the components of the filter module occur as a result of the exhaust air temperatures.
An easily producible configuration of the separable connection between the filter insert and the filter housing consists, according to a further claim, in providing a non-positive snap connection, especially with a spherical locking projection that engages in a locking recess.
According to a further embodiment, the filter module can be equipped at the outlet opening, in other words at the visible front side, with a covering grid plate. This offers protection against unintended contact with the filter elements, especially if these are wetted with fluid, while also offering visual design possibilities for the front side of the filter module. With a lamellar configuration of the grate rods, the flow of the exiting, filtered air can also be influenced, for example deflecting it in a specific direction. For attaching the covering grid plate, all possible types of attachment, such as screws, clamps, adhesives, etc, are again possible.